HP 600 Series, Services And Applications

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Encapsulation Filters
Filters enable the bridge to either selectively relay or drop a particular frame
on the basis of header fields used with each of the four encapsulation
methods supported by the bridging service. These encapsulation methods
are as follows:
Ethernet
IEEE 802.2 logical link control
IEEE 802.2 LLC with SNAP header
Novell proprietary
Figures 33 through 36 illustrate each method of encapsulation.
Figure 33. Ethernet Encapsulation
Ethernet version 2 encapsulation (shown in figure 33) prefixes an eight-octet
preamble, six octets of destination-address information, six octets of source-
address information, and two octets of protocol-type information to the
frame. It appends a four-octet frame check sequence to the frame.
Figure 34. 802.2 Encapsulation
802.2 encapsulation (shown in figure 34) prefixes one octet of destination
service access point identification, one octet of source service-
access-point identification, and one octet of control information to the
frame. The 802.2 frame, in turn, will be encapsulated within a MAC-level
media-specific frame.
Preamble
8 octets
Destination
6 octets
Source
6 octets
Type
2 octets
Data
46–1500 octets
DSAP
1 octet
SSAP
1 octet
Control
1 octet
Data
46–1500 octets
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Bridging Service
Encapsulation Filters
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